1. Field of the Invention
The present invention relates to a rotary electric machine having a Lundell type pole core in the rotor thereof.
2. Description of the Related Art
An alternator for a vehicle includes a rotor having a Lundell type pole core which is composed of a pair of core members having a plurality of claw poles which extend axially. As the electric loads of a vehicle has increased, the amount of necessary output power from the alternator has increased. This has necessitated a reduction in the leakage flux between the pole cores.
U.S. Pat. No. 5,483,116 (or JP-A-7-123664) proposes a rotor in which a zigzag-ring-shaped magnet holder is disposed between a pair of pole members. The rotor holds a plurality of permanent magnets each of which is disposed between two adjacent claw poles. Therefore, the spaces between the pole members must have precise sizes to secure the holder. This necessitates precise machining.
JP-A-7-312854 proposes a rotor of an alternator which has covered permanent magnets. The covered permanent magnets are welded to the claw poles. In order to secure the permanent magnets, it is also necessary to have claw poles with a precise size. This necessitates additional machining.
U.S. Pat. No. 5,306,977 (or JP-A-207716) proposes a rotor in which permanent magnets are held by two non-magnetic rings. The rings are retained inside the claw poles. This structure also requires precise machining to reliably secure the permanent magnets.